We open walls in Arlington, DC, and Maryland homes every week and see the same regrets. Here's what to replace, rough-in, and demand from your contractor while access is cheap — before finishes lock in the expensive path.
Reviewed against real remodel punch lists · VA Plumbing Lic. 2710075081 · Contractor Lic. 2705180998 · Updated July 2026
While the walls are open
Replace the pipes — especially galvanized, polybutylene, or very old copper
If your home was built before 1960 (galvanized), between 1978–1995 (polybutylene), or has 50+ year-old copper, this is the cheapest repipe you will ever get. The demolition is already paid for.
Pressure-test, then photograph every wall before drywall
A phone photo of every open wall is a free, permanent map of every pipe, valve, and wire in your house. Ask your GC to schedule you a walkthrough the day before insulation.
Replace the cast iron stack and camera the sewer line first
Don't tie brand-new bathrooms into a 70-year-old drain line you've never seen the inside of. A camera inspection before rough-in tells you whether the lateral needs repair while yard access is easy.
Add a hot water recirculation return line — even without the pump
Running one extra pipe now costs very little. It's what makes “instant hot water at every tap” possible later.
Keep supply lines out of exterior walls
In our climate, plumbing in an exterior wall is a burst pipe waiting for the right January. If there's no alternative, demand insulation on the wall side of the pipe — and insulate all hot lines regardless.
Rough-in the future while it's cheap
Outlet + water at every toilet for a bidet someday; basement bathroom stub-outs; gas stub for grill/generator/outdoor kitchen; upsize the water service (3/4" to 1") if you're adding bathrooms.
Valves and shutoffs
Insist on a PRV — even if they say code doesn't require it
Street pressure in much of NoVA, DC, and Maryland runs high, and everything downstream — faucet cartridges, supply lines, the water heater — dies young without a pressure reducing valve.
A PRV means you also need a thermal expansion tank
A PRV creates a “closed system”: heated water has nowhere to expand, so pressure spikes hammer your water heater. The expansion tank is the part that protects the heater.
Quarter-turn ball valves everywhere
Replace every crusty multi-turn stop under sinks and toilets while access is easy. When you need a shutoff, you need it to actually turn.
New main shutoff + a smart leak shutoff while the main is exposed
If the main shut-off valve is original to the house, replace it. With the main line exposed, adding a Moen Flo or Phyn auto-shutoff is often a short job — many insurers discount your premium for it.
Shutoffs per bathroom or branch
Zone valves mean one future repair shuts down one bathroom — not the whole house on a Tuesday morning.
Water hammer arrestors
At the washing machine, dishwasher, and ice maker lines. Fast-closing solenoid valves are what make pipes bang.
Showers and baths
Every shower valve needs an access panel. No exceptions.
The valve lives behind the handle wall. If the other side becomes a wine rack, mural, or giant-format tile, the day the valve leaks you're demolishing something you love. Frame an access panel — closets and cabinets hide them beautifully.
Fancy showers are wonderful — until they leak
Multi-head, digital, and steam showers are more plumbing, more connections, and more things needing future service. Design in serviceability: access panels, isolation valves, and a valve platform with parts availability.
Choose valve brands you can still get parts for in 2046
Delta, Moen, and Kohler cartridges will be at the supply house for decades. The obscure imported trim that won the design award may be discontinued in five years — and then the whole wall opens up.
Flood-test the pan, and demand real waterproofing
The shower pan gets flood-tested with standing water before tile goes down, and waterproofing means a membrane system (Schluter, wedi, or equivalent) — not just cement board and hope.
Keep extra tiles. Always.
A box of your exact tile in the attic turns a future repair from “re-tile the bathroom because the dye lot no longer exists” into a patch nobody will ever spot.
Freestanding tubs and floor-mounted fillers
Rough-in placement must be exact before the slab or subfloor closes — and ask how anyone services the filler later.
Jetted and air tubs need motor access
Same rule as shower valves: if the motor is entombed in a tiled skirt, the tub's first repair includes demolition.
Water heater and laundry
A sediment filter before the water heater
Cheap insurance that makes the heater last dramatically longer — it catches grit that otherwise settles in the tank or scales a tankless heat exchanger.
Pan, drain, and braided lines
Drain pan piped to an actual drain under the water heater, braided stainless supply lines on every fixture and appliance, and an outlet box with arrestors at the washer. Upstairs laundry? A pan and a floor drain are non-negotiable.
Paper trail
Keep a folder of every valve and fixture model number
Spec sheets, model numbers, finish names. Future repairs become a parts order instead of detective work. (We keep these on file for our remodel clients.)
Permits and a licensed plumber
Unpermitted plumbing surfaces at the worst times: resale inspections and insurance claims. Verify the license — VA Plumbing Lic. 2710075081 · Contractor Lic. 2705180998.
FAQs
Should I replace plumbing during a remodel?
If walls are opening anyway and your pipes are galvanized, polybutylene, or 50+ year-old copper — yes. Remodel-time repiping costs a fraction of doing it later and protects the finishes you're about to invest in.
Do I need a PRV if code doesn't require one?
We recommend one in nearly every NoVA/DC/MD home. High street pressure shortens the life of every fixture and appliance, and a PRV with an expansion tank is cheap protection.
What is a sediment filter for a water heater?
A whole-house pre-filter installed on the cold line ahead of the water heater. It traps grit and sediment that would otherwise accumulate in the tank or scale a tankless unit, extending its life.
Why does a shower valve need an access panel?
The mixing valve behind the handle will eventually need a cartridge or full replacement. An access panel on the back side of the wall turns that into a one-hour job instead of demolition of tile, built-ins, or feature walls.
Planning a remodel in Arlington, NoVA, DC, or Maryland?
Have us walk the job before drywall — a one-visit plumbing punch list (camera the sewer, pressure test, PRV/expansion check) that protects everything you're about to build.